Durable, heat-resistant multi-layer coatings and coated articles

ABSTRACT

A method of providing a durable protective coating structure which comprises at least three layers, and which is stable at temperatures in excess of 400° C., where the method includes vapor depositing a first layer deposited on a substrate, wherein the first layer is a metal oxide adhesion layer selected from the group consisting of an oxide of a Group IIIA metal element, a Group IVB metal element, a Group VB metal element, and combinations thereof; vapor depositing a second layer upon said first layer, wherein said second layer includes a silicon-containing layer selected from the group consisting of silicon oxide, silicon nitride, and silicon oxynitride; and vapor depositing a third layer upon said second layer, wherein said third layer is a functional organic-comprising layer. Numerous articles useful in electronics, MEMS, nanoimprinting lithography, and biotechnology applications can be fabricated using the method.

This application claims priority under 35 U.S.C. 120 as acontinuation-in-part of U.S. application Ser. No. 11/528,093 (nowabandoned), filed on Sep. 26, 2006 now abandoned, which claimed priorityas a continuation of U.S. application Ser. No. 11/112,664 (now U.S. Pat.No. 7,776,396), filed on Apr. 21, 2005, which claimed priority as acontinuation-in-part of U.S. application Ser. No. 10/996,520 (nowabandoned), filed on Nov. 23, 2004 now abandoned, which claimed priorityas a continuation-in-part of application Ser. No. 10/862,047 (now U.S.Pat. No. 7,638,167), filed on Jun. 4, 2004. The present applicationclaims priority under 35 U.S.C. 119 to U.S. Provisional Application No.60/930,290, titled: Durable Multi-layer Coatings and Coated Articles,which was filed on May 14, 2007. U.S. Provisional Application No.60/930,290 is hereby incorporated by reference in its entirety. Thepresent application is also related to the following applications, eachof which is hereby incorporated by reference in its entirety: U.S.application Ser. No. 10/759,857 (now abandoned), filed Jan. 17, 2004,and titled “Apparatus and Method for Controlled Application of ReactiveVapors to Produce Thin Films and Coatings”; U.S. application Ser. No.11/295,129 (now U.S. Pat. No. 7,695,775), filed Dec. 5, 2005, and titled“Controlled Vapor Deposition of Biocompatible Coatings Over SurfaceTreated Substrates”; U.S. application Ser. No. 10/912,656 (nowabandoned), filed Aug. 4, 2004, and titled “Vapor Deposited FunctionalOrganic Coatings”; U.S. application Ser. No. 11/123,487 (now abandoned),filed May 5, 2005, and titled “Controlled Vapor Deposition ofBiocompatible Coatings for Medical Devices”; and U.S. patent applicationSer. No. 11/447,186 (now U.S. Pat. No. 8,067,258), filed Jun. 5, 2006,and titled “Protective Thin Films For Use During Fabrication ofSemiconductors, MEMS, and Microstructures.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

A durable, heat-resistant functional hydrophobic, hydrophilic, orreactive coating deposited using vapor deposition techniques on avariety of substrate materials.

2. Brief Description of the Background Art

This section describes background subject matter related to theinvention, with the purpose of aiding one skilled in the art to betterunderstand the disclosure of the invention. There is no intention,either express or implied, that the background art discussed in thissection legally constitutes prior art.

Substrate materials, micro structures, and components coated withhydrophobic and hydrophilic films have, in recent years, found manyapplications in a variety of industries including automotive,semiconductors (SEMI), micro-electro-mechanical systems (MEMS), bio- andmicro-fluidics, nano-imprint lithography (NIL), and others. The mainmotivation and purpose of such coatings is the desire to obtain aspecific surface property and/or protection of the material surfacewithout changing the base substrate material itself. For example,self-assembled monolayers (SAM) formed from hydrocarbon and fluorocarboncoatings provide hydrophobic surfaces characterized by a very lowsurface energy and low reactivity. Such films prevent wetting, improvede-wetting, and facilitate cleaning in the case of e.g. glass andautomotive industry parts. SAM coatings are also used to preventstiction in MEMS and NIL applications, and can enhance protection frommoisture and environmental contamination in packaging of semiconductorsand display devices. Conversely, hydrophilic films are used inapplications where an improvement in surface wetting is desired, such asin the case of microfluidic devices, bio-chips, anti-fog and otherrelated applications.

The liquid and vapor phase coating techniques known to provide suchfunctional surfaces frequently include substrate surface silanizationusing silane based precursors. The most commonly used substrate surfacereaction mechanisms for silane precursor attachment are hydrolysis of achlorosilane and its reaction with hydroxyl groups present on thesubstrate surface. Another possibility is the attachment of an amineterminated alkylsilane to the substrate surface. Particularly, covalentreaction with the substrate surface, whether with hydroxyl groups orother groups which are strongly attached to the substrate surface,provides a strong bonding of the silane to the substrate surface.Covalent bonding provides a relatively high mechanical and chemicalstability of the films. With respect to reaction with hydroxyl groups,this reaction requires a high concentration of the hydroxyl groups onthe substrate surface, and is therefore limited to substrates exhibitingsuch groups, e.g. silicon, quartz, and various oxides.

Deposition of SAM functional coatings on substrate materials other thanthose exhibiting a high concentration of hydroxyl groups may be achievedusing an adhesion layer-forming precursor. Many of these precursors formnon-covalent bonds with the substrate material surface, and typicallythe overall coating structure including the adhesion layer with SAMattached exhibits a relatively inferior durability. This is particularlytrue when there is mechanical abrasion of the exterior, SAM-coatedsurface.

The use of specialized adhesion promoting layers, which adhere well toparticular substrate materials and provide a high concentration ofhydroxyl groups for subsequent reaction with a silane-based hydrophilicor hydrophobic coating precursor which is in vapor form (by way ofexample and not by way of limitation), has been proposed. Adhesionlayers of silicon oxide or various metal oxides have been used becausethese exhibit a high density of surface hydroxyl states. Adhesion of asilicon oxide or metal oxide layer to the substrate material, as well asquality and durability of the top functional layer applied over theadhesion layer determine the ability of a SAM-coated surface to meet thedemanding requirements in commercial applications. In commercialapplications, the SAM-coated surface undergoes prolonged exposure tomanufacturing and environmental factors such as: radiation, liquidimmersion, mechanical friction, or high temperature.

In pending application Ser. No. 10/862,047 filed Jun. 4, 2004 (Pub. No.2005/0271809) titled “Controlled Deposition of Silicon-ContainingCoatings Adhered by an Oxide Layer”, and in pending application Ser. No.11/978,123 filed Oct. 26, 2007 (Pub. No. 2008-0081151A1) titled “VaporDeposited Nanometer Functional Coating Adhered By An Oxide Layer”,Kobrin et al. described methods of depositing functional SAM coatingsusing oxide films as adhesion layers on various substrates. The minimumthickness of the silicon dioxide adhesion layers grown by molecularvapor deposition (MVD) was said to be dependent on the substratematerial used. Films as thick as 200 Å were required in the case of somesubstrate materials to assure relative stability of the adhesion layerupon water immersion. Metal oxides and in particular aluminum oxide andtitanium oxide coatings were proposed as adhesion layers.

With regard to the use of metal oxide films in electronic devicepackaging, Featherby et al., in U.S. Pat. No. 6,963,125 issued Nov. 8,2005, and entitled “Electronic Device Packaging” described anencapsulation method consisting of two layers: 1) an inorganic layerwhich prevents moisture intake and 2) an outside organic layerprotecting the inorganic layer, in which both layers are said to beintegrated with an electronic device plastic package. The organic layerwhich is applied directly over the inorganic layer is said to bepreferably Parylene C (Col. 10), which is a relatively thick material,expensive, and is said to serve the function of protecting the brittleinorganic coating during manufacturing steps such as injection molding.

The use of dual layer films containing ALD alumina and a thinalkylaminosilane functional SAM coating attached to alumina was proposedfor wear and stiction protection in MEMS by George et al. in U.S.application Ser. No. 10/910,525 filed Aug. 2, 2004 (Pub. No. US2005/0012975), and entitled “Al2O3 Atomic Layer Deposition to Enhancethe Deposition of Hydrophobic or Hydrophilic Coatings onMicro-electromechanical Devices”. In addition, George et al., in U.S.application Ser. No. 10/482,627 filed on Jul. 16, 2002 (Pub. No. US2004/0194691), and entitled “Method of Depositing an Inorganic Film onan Organic Polymer”, described the use of an ALD metal oxide films asmoisture and gas barriers on polymeric substrates.

With the development of electroluminescent devices, flat panel displays,organic light emitting diodes (OLEDs), and flexible electronics there iseven a stronger need to protect such devices from performancedegradation due to oxygen and moisture. PVD and ALD alumina films havebeen tried extensively for such applications, however, the single ordual layer protective coatings of the kind described above have beenfound to be inadequate.

Various multilayer film laminates, have been explored as a hermeticglass package replacement for use in OLEDs. For example, Haskal et al.in U.S. Pat. No. 5,952,778, issued Sep. 14, 1999, entitled “EncapsulatedOrganic Light Emitting Device” proposed an encapsulation scheme toprevent the OLED device from oxidation and degradation due to ambientoxygen and water. The protective encapsulation comprises threecontiguous layers: a first layer of passivation metal such as gold,silver, indium, aluminum or transition metal; a second layer of thinfilm deposited dielectric material such as silicon dioxide or siliconnitride; and, a third layer of a hydrophobic polymer. Park et al. inU.S. Pat. No. 6,926,572, issued Aug. 9, 2005, entitled “Flat PanelDisplay Device and Method of Forming Passivation Film in the Flat PanelDisplay Device” proposed the use of an organic insulating film and/or ametal film in combination with an inorganic insulating film to provide atwo layer or three layer passivating film. (Claim 14, for example) Inparticular, the reference teaches that it is possible to additionallyform an organic insulating film before and/or after the inorganicinsulating film is formed. (Col. 3, lines 47-50) Typically, the organicinsulating film is said to be deposited by TCVDPF (thermal chemicalvapor deposition polymer formation). When a metal film is part of thepassivating film, it is proposed that the metal film is the first layerof a two or three layer passivation film, deposited over a cathodeelectrode which makes up part of the organic light emitting device.(Col. 4, lines 48-57)

Despite efforts like those described above, the functionality of thepassivating coatings developed has been lacking, and the cost of thethick multilayer films proposed is high. The search for abetter-performing and thinner protective films which meet cost andperformance requirements continues, in an effort to commercialize amultitude of prototype devices in volume production.

SUMMARY

Described herein are film deposition methods and multi-layeredstructures which provide both an improved adhesion to substrates and animproved durability of an exterior functional organic layer such as aSAM layer. The method and the structures formed allow the multilayeredfilm to be deposited on a multitude of substrates which exhibit a lowdensity of hydroxyl groups. The method, and the multilayer filmsproduced using the method are especially valuable in applications suchas ink-jets, microfluidics, disk drives, nano-imprint lithography (NIL),packaging, and many others where conventional SAM deposition methods donot provide an exterior surface which meets durability requirements.

The multi-layered coating structures described subsequently herein, inthe Detailed Description of Typical Embodiments, are designed so thatthe exterior layer of the structure provides durable hydrophilic and/orhydrophobic surface properties. The multi-layered coating structurescomprise at least three layers, including a first adhesion layer whichis typically a metal oxide; a second protective layer which includes asilicon-containing layer and typically a silicon-containing oxide; and athird exterior functional layer. The second protective layer may includemore than one layer, which includes a silicon-containing layer and ametal oxide layer. The metal oxide adhesion layer is typically depositedusing Atomic Layer Deposition (ALD) techniques, while the protectivelayer is deposited using a CVD technique, which is often a technique ofthe kind performed in an Molecular Vapor Deposition (MVD®) processingsystem. Molecular Vapor Deposition is a specialized form of chemicalvapor deposition.

In embodiments of the invention which are described subsequently in theDetailed Description of Exemplary Embodiments, sequential layerdepositions of either MVD® or ALD, or a combination of both may be usedto produce various three-layer coatings. The individual coating layersare stacked in a manner to provide advantageous adhesion to anunderlying substrate, an overlying layer which protects the adhesionlayer, and an exterior functional organic layer. The exterior functionalorganic layer frequently is a self-assembled-monolayer (SAM). Thecombination of the adhesion layer, overlying protective layer, andexterior functional organic layer provides unexpected functionality inwhich the multi-layered coating structure can withstand highertemperatures than previously contemplated for an organic SAM, increasedmechanical stress with reduced wear, and immersion in liquids.

The adhesion layer which is applied directly over the substrate to becoated is an oxide of a Group IIIA, or Group IVB, or Group VB metalelement; the protective layer overlying the metal oxide is asilicon-containing layer selected from the group consisting of siliconoxide, silicon nitride, or silicon oxynitride; and, the exteriorfunctional layer overlying the protective layer is formed from afunctional organic compound. Frequently the functional organic compoundforms a self assembled monolayer (SAM). The adhesion layer is oftenapplied using an ALD technique, while the protective layer is oftenapplied using a chemical vapor deposition technique, which is frequentlythe MVD® chemical vapor deposition technique, which has recently beendescribed in the published art. The exterior functional layer is alsodeposited using a chemical vapor deposition technique, which is oftenthe MVD® technique. The adhesion layer is typically deposited usingprecursors which include an organometallic compound. The protectivelayer is typically deposited using precursors which include a silane,and some of the most advantageous embodiment protective layers aredeposited from organic silanes. The exterior functional layer istypically deposited from a precursor functionalized alkylchloro silaneor a functionalized alkylamino silane. The individual coating layers arestacked in a way to provide an excellent adhesion to the substrate, toprovide mechanically strength, and to provide a durable functionalcoating surface. The durable functional coating surface is typicallyorganic in nature, yet able to withstand high temperature, in excess of400° C., mechanical stress, and immersion in liquids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram 100 of a substrate 102 with an overlyingthree-layer coating which includes a metal oxide adhesion layer 104, asilicon comprising layer 106 which protects adhesion layer 104, and anexterior functional layer 108.

FIG. 2 shows a graph 200 illustrating the DI Water Contact Angle onscale 204, as a function of the substrate Temperature at which ahydrophobic coating of a kind known in the prior art was heat treated,on scale 202. This is a comparative example of the performance of a twolayer coating, where the first layer deposited on the substrate is anALD-deposited aluminum oxide, and the second, exterior layer is a SAMformed using a (Heptadecafluoro-1,1,2,2, tetrahydrodecyl)trichlorosilane (FDTS) precursor in combination with water. Curve 206illustrates coating performance of the coating on a copper substrate.Curve 208 illustrates coating performance on a stainless steelsubstrate. Curve 210 illustrates coating performance on a siliconsubstrate.

FIG. 3 shows a graph 300 illustrating the DI Water Contact Angle onscale 304, as a function of the substrate Temperature, at which anotherhydrophobic coating of a kind known in the prior art was heat treated,on scale 302. This is a comparative example of the performance of a twolayer coating, where the first layer deposited on the substrate is anALD-deposited titanium oxide, and the second, exterior layer is a SAMformed using a FDTS precursor in combination with water. Curve 306illustrates coating performance of the coating on an aluminum substrate.Curve 308 illustrates coating performance on a stainless steelsubstrate. Curve 310 illustrates coating performance on a nickelsubstrate. Curve 312 illustrates coating performance on a goldsubstrate. And, Curve 314 illustrates coating performance on a siliconsubstrate.

FIG. 4 shows a graph 400 illustrating the DI Water Contact Angle onscale 404, as a function of the substrate Temperature on Scale 402, fora variety of hydrophobic coatings. The underlying substrate on which thecoatings were deposited was a silicon wafer substrate. This graph 400illustrates both two layer coatings of the kind which were previouslyused, and coatings which are embodiments of the present invention, forpurposes of comparison. Due to the number of substrates and differenttypes of coatings which were tested, the description of the coatings andsubstrates is provided only in the Detailed Description Of TypicalEmbodiments, which is presented subsequently herein.

FIG. 5 shows a graph 500 illustrating the DI Water Contact Angle onscale 504, as a function of the substrate Temperature on Scale 502.Graph 500 shows Curves 506 and 508 for a two-layerAlOx/(Nonafluoro-1,1,2,2,-tetrahexyl) tris (dimethylamino)silane (PF6)coating deposited at two different thicknesses on a silicon wafersubstrate. The Curves 506 and 508 are shown for comparison purposesagainst Curves 510 and 512, which show AlOx/BTCSE Ox/PF6 deposited attwo different thicknesses on a silicon wafer substrate. This graph 500illustrates both coatings of the kind previously used and coatings whichare embodiments of the present invention, for purposes of comparison.

FIG. 6 shows a graph 600 illustrating the DI Water Contact Angle onscale 604, as a function of the Number of Days of Water Immersion onScale 602, for a two-layer AlOx/FDTS coating deposited on threedifferent substrates, compared with a three-layer AlOx/SiCl₄ Ox/FDTScoating on two substrates. The two-layer coating data is provided forpurposes of comparison of two-layer coatings of the kind previously usedwith coatings which are embodiments of the present invention.

FIG. 7 shows a graph 700 illustrating the DI Water Contact Angle onscale 704, as a function of the number of days immersion in DI Water onscale 702. The three-layer coatings were deposited on a SU8 resistmaterial substrate. Curve 706 represents the change in DI water contactangle for an AlO_(x)/TiO_(x)/FDTS coating. Curve 708 represents thechange in DI water contact angle for an AlO_(x)/SiCl₄-generatedSiO_(x)/FDTS coating. Curve 710 represents the change in DI watercontact angle for an AlO_(x)/BTCSE-generated SiOx/FDTS coating.

FIG. 8 shows a graph 800 illustrating the DI Water Contact Angle onscale 804, as a function of the substrate Temperature on scale 802.Graph 800 shows Curve 810 for a FDTS coating directly on a silicon wafersubstrate; Curve 806 for a two-layer AlO_(x)/FDTS on the silicon wafersubstrate; Curve 808 for a three-layer coating of AlO_(x)/TiO_(x)/FDTSon the silicon wafer substrate; Curve 812 for a three-layer coating ofAlO_(x)/SiCl₄-generated SiO_(x)/FDTS; and, Curve 814 for a three-layercoating of AlO_(x)/BTCSE-generated SiO_(x)/FDTS. This graph 800illustrates both coatings of the kind previously used and coatings whichare embodiments of the present invention, for purposes of comparison.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As a preface to the detailed description, it should be noted that, asused in this specification and the appended claims, the singular forms“a”, “an”, and “the” include plural referents, unless the contextclearly dictates otherwise.

When the word “about” is used herein, this is intended to mean that thenominal value presented is precise within ±10%.

The exemplary embodiments of the invention described below are toillustrate the heat-resistant multilayered coatings of the invention.The described embodiments are not to limit the scope of the invention,as one skilled in the art will be able to use the description to extendthe invention to the use of other, similar materials. The method offorming each layer of the multi-layered coating requires a particularsequence of deposition steps to produce the unique coatings; however,the methods of depositing individual layers of the coatings are known inthe art in general.

The multi-layered coating structures comprise at least three layers ofdifferent composition, but may comprise additional layers. The threerequired layers are a first adhesion layer which is used to attach thecoating structure to an underlying substrate; a second,silicon-comprising layer which adds to the mechanical, chemical, andthermal stability of the coating structure, and provides excellentadhesion to organic-based surfaces; and, a third exterior layer whichprovides surface functionality for the coating. The secondsilicon-comprising layer may be replaced by more than one layer,provided at least one of the replacement layers is a silicon-comprisinglayer. Frequently, the third exterior layer is a self-assembledmonolayer (SAM) The presence of the silicon-comprising layer improvesthe durability of an exterior functional SAM layer.

The method and the structures formed allow the multilayered film to bedeposited on a multitude of substrates which exhibit a low density ofhydroxyl groups, such as particular metals, plastics and composites. Themulti-layered coating structures are designed so that the exterior layerof the structure provides durable hydrophilic and/or hydrophobic surfaceproperties. The exemplary embodiments described below are designed toprovide hydrophobic surface properties, because coatings which provide ahydrophobic surface exhibiting wear-resistance and high temperaturestability are particularly difficult to produce. One skilled in the artwill recognize that hydrophilic multi-layered coatings in accordancewith the present invention can be produced by using a SAM which provideshydrophilic functional properties on its presented exterior surface. Themulti-layered coating structures with hydrophobic surface properties arein high demand for use in MEMS, nanoimprint lithography (NIL),microfluidics, and semiconductor packaging, for example and not by wayof limitation.

As previously discussed, the methods which are used for vapor depositionof the coating structures may be Molecular Vapor Deposition (MVD®),which is a specialized form of chemical vapor deposition currently knownin the art, or may be Atomic Layer Deposition (ALD), another form ofchemical vapor deposition which is currently known in the art, or may bea combination of these two vapor deposition techniques. In embodimentsof the invention which are described, sequential layer depositions ofeither MVD® or ALD, or a combination of both may be used to producevarious multi-layered coatings. The individual coating layers arestacked in a manner to provide advantageous adhesion to an underlyingsubstrate, an overlying layer which protects the adhesion layer and/orprovides mechanical strength to the overall coating structure, and anexterior functional organic layer. The combination of the adhesionlayer, overlying protective layer, and exterior functional organic layeris tailored to the substrate and can provide unexpected functionality inwhich the multi-layered coating structure can withstand highertemperatures than previously contemplated for an organic SAM, canwithstand increased mechanical stress with reduced wear, and canwithstand immersion in liquids for extended periods of time.

The adhesion layer which is applied directly over the substrate to becoated is an oxide of a Group IIIA, or Group IVB, or Group VB metalelement; the protective layer overlying the metal oxide is either asilicon-containing layer selected from the group consisting of siliconoxide, silicon nitride, or silicon oxynitride, or may be more than onelayer, provided at least one silicon-containing layer is included; and,the exterior functional layer overlying the protective layer is formedfrom a functional organic compound. Frequently the functional organiccompound forms a SAM. The adhesion layer is often applied using an ALDtechnique, while the protective layer is often applied using a chemicalvapor deposition technique, which is frequently the MVD® chemical vapordeposition technique. The exterior functional layer may also bedeposited using a chemical vapor deposition technique, which is oftenthe MVD® technique. The adhesion layer is typically deposited usingprecursors which include an organometallic compound. The protectivelayer is typically deposited using precursors which include either aninorganic silane or an organic silane. The exterior functional layer istypically deposited from a precursor functionalized alkylchloro silaneor a functionalized alkylamino silane.

EXAMPLES OF ILLUSTRATIVE EMBODIMENTS

The coating layers described were vapor deposited from liquid precursorsobtained from Gelest Inc. and Sigma. The coating layers were vapordeposited using the MVD® 100 vapor deposition system manufactured byApplied Microstructures, Inc. Surface cleaning and hydroxylation ofsubstrate surfaces (when beneficial) were performed in-situ in the MVD®100 vapor deposition system using a remotely-generated oxygen plasmasource. The metal oxide adhesion layers; the silicon-containing layerwhich protects the adhesion layer and/or provides excellent adhesion toexterior organic-based surfaces; and, the exterior functional organiclayer were grown sequentially at temperatures between about 50° C. andabout 80° C., without exposure of the substrate to ambient conditionsduring the deposition processes. DI Water Contact Angles were determinedusing a Rame-Hart Goniometer.

Although one skilled in the art can appreciate that various differentchemical reactions and precursor chemistries can be used for depositionof individual films in the multi-layer film stack, during deposition ofthe coating layers of the examples described below, the depositionmethod and precursor chemistry shown in Table One, below, were used.

TABLE ONE Coating Layer Type Deposition Method Precursor Chemistry MetalOxide ALD MO 1: TMA, H₂O MO 2: TiCl₄, H₂O Silicon-Comprising Layer MVD ®SO 1: BTCSE, H₂O SO 2: SiCl₄, H₂O Functional Exterior MVD ® F 1: FDTS,H₂O Organic Layer F 2: PF6Legend for chemicals in Table One: Trimethylaluminum (TMA); Titaniumtetrachloride (TiCl₄); Bis(trichlorosilyl)ethane (BTCSE); Silicontetrachloride (SiCl₄); (Heptadecafluoro-1,1,2,2, tetrahydrodecyl)trichlorosilane (FDTS); Nonafluoro-1,1,2,2-tetrahydrohexyltris(dimethylamino)silane (PF6); and water vapor (H₂O).

ALD Process Example—formation of metal oxide adhesion layers. An ALDmethod was used to deposit aluminum oxide or titanium oxide as the baseadhesion layer. While other methods of CVD deposition of the metal oxideadhesion layer may be used, we have found that use of ALD providesexcellent adhesion to an underling substrate in general. The ALDreaction consisted of alternating exposures of the substrate toreactants A (first reactant charged to the process chamber) and B(second reactant charged to the process chamber) in a number ofrepetitive AB cycles with a nitrogen gas purge and pump steps in betweenthe reactant exposures to remove the residual non-adsorbed, non-reactedchemicals. In one ALD cycle the reactants were introduced sequentially,adsorbed on the surface, and purged. Typically 1.0-1.3 Å of aluminumoxide film is deposited in one cycle. The reaction cycle was thenrepeated a number of times to achieve ALD film thickness of 20 Å-100 Å,typically 50 Å-100 Å. The chemical precursors listed in Table One wereused to form adhesion layers in an MVD® 100 Vapor Deposition Systemavailable from Applied Microstructures, Inc., San Jose, Calif. with thefollowing processing parameters: The TMA or TiCl₄ which was applied tothe substrate during the first step of a deposition cycle was applied ata partial pressure which was in the range of 0.2-5 Torr. The water vaporwhich was applied to the substrate during the second step of adeposition cycle was applied at a partial pressure ranging about 0.5-20Torr. The reaction temperature in each step of the deposition cycle wasin the range of 20-150° C. (typically 40-70° C.). The number ofsequential cycle repetitions ranged 20-100, with nitrogen purge/pumpin-between injections. An oxygen plasma step using a remote plasmasource was used to pre-clean the substrates prior to film deposition.

MVD® Oxide Process Example—formation of silicon oxide inter-layer.Hydrophilic silicon oxide inter-layer films were deposited by themolecular vapor deposition (MVD®) method described previously herein,with reference to pending U.S. patent applications. The MVD® VaporDeposition System was used and the reaction parameters were as follows.The BTCSE or SiCl₄ which was applied to the substrate during the firststep of a deposition cycle was applied at a partial pressure which wasin the range of 1-6 Torr. The water vapor which was applied during thesecond step of a deposition cycle was applied at a partial pressureranging about 50 Torr to about 100 Torr. The reaction temperature ineach step was in the range of about 25° C. to about 80° C. (typicallyabout 40° C. to about 70° C.). The duration of the film growth reactionwas about 5 min. to about 15 min., typically resulting in the formationof a film thickness ranging from about 50 Å to about 100 Å. However,thinner films down to about 20 Å, or thicker films up to about 200 Å maybe deposited for particular applications.

MVD® SAM Process Example—deposition of fluorocarbon self-assembledmono-layer. Hydrophobic fluorocarbon SAM coatings were deposited by themolecular vapor deposition (MVD®) method described previously hereinwith reference to pending patent applications. The MVD® Vapor DepositionSystem was used and the reaction parameters were as follows. The FDTS orPF6 partial pressures were in the range of about 0.1 Torr to about 0.8Torr and the water vapor partial pressure was in the range of about 2Torr to about 5 Torr. The reaction chamber temperature was within therange of about 20° C. to about 100° C., (typically about 40° C. to about70° C.). The reaction time ranged from about 5 min to about 30 min.

A Three-Layer film stack 100 is illustrated in FIG. 1, which shows asubstrate 102 with an overlying three-layer coating which includes afirst adhesion layer 104 which is a metal oxide layer (typicallydeposited using ALD, not by way of limitation); a silicon-comprisinglayer 106 which protects adhesion layer 104 and/or adds mechanicalstability to the three-layer structure (which may be silicon oxide,silicon nitride, or silicon oxynitride) and improves adhesion to a SAM;and an exterior functional layer 108 (which is frequently a SAM). Asdiscussed previously, it is contemplated that the silicon-comprisinglayer 106 may be replaced by multiple layers, where one of the multiplelayers is a silicon-containing layer. For example, and not by way oflimitation, the silicon-comprising layer 106 might include a siliconoxide layer generated from an organic silane precursor and a metal oxidelayer generated from an organic metal oxide precursor.

The functional layer 108 may be formed from a precursor selected fromthe group consisting of(heptadecafluoro-1,1,2,2,-tetrahydrodecyl)trichlorosilane (FDTS),(tridecafluoro-1,1,2,2,-tetrahydrooctyl)tricholorsilane (FOTS),undecenyltrichlorosilanes (UTS), vinyl-trichlorosilanes (VTS),decyltrichlorosilanes (DTS), octadecyltrichlorosilane (OTS),dimethyldichlorosilanes (DDMS), dodecenyltricholrosilanes (DDTS), andaminopropylmethoxysilanes (APTMS), by way of example and not by way oflimitation. The OTS, DTS, UTS, VTS, DDTS, FOTS, and FDTS are alltrichlorosilane precursors. The other end of the precursor chain is asaturated hydrocarbon with respect to OTS, DTS, and UTS; contains avinyl functional group, with respect to VTS and DDTS; and containsfluorine atoms with respect to FDTS and FOTS (which also has fluorineatoms along the majority of the chain length). Other useful precursorsinclude 3-aminopropyltrimethoxysilane (APTMS), which provides aminofunctionality, and 3-glycidoxypropyltrimethoxysilane (GPTMS), whichprovides epoxide functionality. One skilled in the art of organicchemistry can see that the vapor deposited coatings from theseprecursors can be tailored to provide particular functionalcharacteristics for a coated surface.

Most of the silane-based precursors, such as commonly used di- andtri-chlorosilanes, for example and not by way of limitation, tend tocreate agglomerates on the surface of the substrate during the coatingformation. These agglomerates can cause structure malfunctioning orstiction. Such agglomerations are produced by partial hydrolysis andpolycondensation of the polychlorosilanes. This agglomeration can beprevented by precise metering of moisture in the process ambient whichis a source of the hydrolysis, and by carefully controlled metering ofthe availability of the chlorosilane precursors to the coating formationprocess. The carefully metered amounts of material and carefultemperature control of the substrate and the process chamber walls canprovide the partial vapor pressure and condensation surfaces necessaryto control formation of the coating on the surface of the substraterather than promoting undesired reactions in the vapor phase or on theprocess chamber walls.

The schematic drawing of a three-layer film stack of the kind shown inFIG. 1 illustrates a typical example of a three-layer coating which maybe deposited in-situ in a single processing chamber. An ALD metal oxideadhesion layer is the first layer, and serves the function of improvingadhesion of subsequently applied layers to the substrate. The substrateis often a polymer or a metal substrate, as these substrates are moredifficult to bond to. In addition to providing adhesion, this metaloxide layer can perform a protective function as moisture or gas barrierlayer.

A Silicon oxide inter-layer, which may be silicon oxide, siliconnitride, or silicon oxynitride adheres well to the metal oxide andenhances bonding and durability of the top functional SAM coating.Silicon oxide deposited using the (MVD®) deposition method is preferredbecause this inter layer provides a clean non-contaminated (grownin-situ) oxide surface highly populated with hydroxyl groups. Finally, ahydrophobic, hydrophilic, or other functional layer is deposited on topof the silicon oxide layer, using an organic-based precursor to providethe desired functionality of the exterior surface.

FIG. 2 shows a graph 200 illustrating the DI Water Contact Angle onscale 204, as a function of the substrate Temperature at which ahydrophobic coating of a kind known in the prior art was heat treated,on scale 202 for a comparative example two layer coating, where thefirst layer deposited on the substrate is an ALD-deposited aluminumoxide (50 Å), and the second, exterior layer is a SAM formed using anFDTS precursor in combination with water. Curve 206 illustrates coatingperformance of the coating on a copper substrate. Curve 208 illustratescoating performance on a stainless steel substrate. Curve 210illustrates coating performance on a silicon substrate. The DI WaterContact Angle degradation of the hydrophobic exterior layer producedfrom a FDTS precursor as the substrate temperature is increased iscatastrophic after about 200° C. for the coating on a copper substrate(illustrated by Curve 206), and after about 260° C. for the coating on astainless steel substrate (illustrated by Curve 208) or a siliconsubstrate (illustrated by Curve 210). Once the DI Water Contact Anglefalls below about 100 degrees, the coating is no longer considered toprovide a functioning hydrophobic surface.

FIG. 3 shows a graph 300 illustrating the DI Water Contact Angle onscale 304, as a function of the substrate Temperature, at which anotherhydrophobic coating of a kind known in the prior art was heat treated,on scale 302. This is a comparative example of the performance of a twolayer coating, where the first layer deposited on the substrate is anALD-deposited titanium oxide (50 Å), and the second, exterior layer is aSAM formed using a Perfluorodecyltrichlorosilane (FDTS) precursor incombination with water. Curve 306 illustrates coating performance of thecoating on an aluminum substrate, where the hydrophobicity has failed(fallen below the 100 degree requirement) at a temperature of about 175°C. Curve 308 illustrates coating performance on a stainless steelsubstrate, where the hydrophobicity has failed at a temperature of about250° C. Curve 310 illustrates coating performance on a nickel substrate,where the failure has occurred at a temperature of about 275° C. Curve312 illustrates coating performance on a gold substrate, where thefailure has occurred at a temperature of about 275° C. And, Curve 314illustrates coating performance on a silicon substrate, where thehydrophobicity has failed at a temperature of about 275° C.

FIG. 4 shows a graph 400 illustrating the DI Water Contact Angle onscale 404, as a function of the substrate Temperature on Scale 402, fora variety of hydrophobic coatings, some of which are two-layer coatingsof the kind described above, and some of which are the multi-layered(three-layered) coatings of present invention embodiments. Theunderlying substrate on which the coatings were deposited was a siliconwafer substrate. This graph 400, which illustrates both two layercoatings of the kind which were previously used, and coatings which areembodiments of the present invention, shows the significant improvementprovided by the present invention.

Curve 406 represents an ALD titanium oxide (80 Å)/MVD® FDTS two-layercoating, where the DI Water Contact Angle fell below 100 degrees atabout 160° C. Curve 408 represents an ALD aluminum oxide (50 Å)/MVD®FDTS two layer coating, where the DI Water Contact Angle fell below 100degrees at about 270° C. Curve 410 represents an ALD titanium oxide (87Å)/MVD® SiCl₄-generated silicon-oxide (93 Å)/MVD® FTDS three-layercoating, where the DI Water Contact Angle did not fall below 100 degreesuntil some point after 500° C. Curve 412 represents an ALD aluminumoxide (94 Å)/MVD® SiCl₄-generated silicon-oxide (148 Å)/MVD® FTDSthree-layer coating, where the DI Water Contact Angle did not fall below100 degrees until about 420° C. Curve 414 represents an ALD titaniumoxide (85 Å)/MVD® BTCSE-generated silicon-oxide (105 Å)/MVD® FTDSthree-layer coating, where the DI Water Contact Angle did not fall below100 degrees until about 425° C. And, Curve 416 represents an ALDaluminum oxide (100 Å)/MVD® BTCSE-generated silicon-oxide (105 Å)/MVD®FTDS three-layer coating, where the DI Water Contact Angle did not fallbelow 100 degrees until some point after 500° C.

For many applications including semiconductor, micro device, ornanoimprint lithography applications, which require downstreamprocessing at temperatures or thermal budgets over 250° C., dual layerfilms utilizing a metal oxide adhesion layer with an overlying SAM arenot sufficiently durable. The result is illustrated in FIGS. 2, 3, and4, which show comparative examples of failures of hydrophobicity of duallayer films at temperatures above 200° C. on multiple substrates. Thisresult is quite surprising, as it is generally known that organicfluorocarbon films deposited directly upon a silicon substrate fail atabout 400° C., depending on the film chemistry.

We have discovered that the performance of fluorocarbon-comprisinghydrophobic exterior films on metal oxide substrates can be greatlyimproved and their stability can be extended to temperatures as high as450° C. by using a silicon-containing layer such as a silicon oxideinterlayer over a metal oxide adhesion layer, prior to deposition of theexterior functional film layer (see FIG. 4). Presence of a silicon oxideintermediate layer over a metal oxide adhesion layer on a substrate,with the fluorocarbon-comprising hydrophobic exterior films attached tothe silicon oxide intermediate layer appears to provide a strongcovalent bonding and effective cross-linking of the FDTS head groups tothe silicon oxide intermediate layer, while the metal oxide adhesionlayer provides a strong bonding to the substrate.

FIG. 4 shows that there is an improvement of DI Water Contact Angle andhigh temperature stability of a hydrophobic (perfluoro)alkylchlorosilane-generated SAM coating on both aluminum oxide and titaniumoxide adhesion layers when a silicon-containing intermediate layer isused between the SAM and the metal oxide. Further, the organic-basedBTCSE-generated intermediate layer provides better temperature stabilitywhen used in combination with an aluminum oxide adhesion layer, whilethe inorganic-based SiCl₄-generated intermediate layer appears toprovide better temperature stability when used in combination with atitanium oxide adhesion layer.

Similar significant improvement of three-layer coating stability incomparison to the respective two-layer coatings was confirmed when thePF6 (Nonafluoro-1,1,2,2-tetrahydrohexyl tris(dimethylamino) silane)precursor was used as the exterior SAM layer of the coating. Use of thesilicon-containing intermediate layer improved the temperaturedurability of the hydrophobic top functional layer by about 100° C. ormore over the published literature data for alkylamino silanes depositedover alumina films.

FIG. 5 shows a graph 500 illustrating the DI Water Contact Angle onscale 504, as a function of the substrate Temperature on Scale 502.Graph 500 shows Curves 506 and 508 for a two-layer AlOx/PF6(Nonafluoro-1,1,2,2-tetrahydrohexyl tris(dimethylamino)silane) coating.Curve 506 represents the two-layer coating when the AlO_(x) layer is 20Å thick, while Curve 508 represents the two-layer coating when theAlO_(x) layer is 95 Å thick.

Although the thicker AlOx layer does appear to improve the stability ofthe two-layer coating somewhat over the 250° C. and 350° C. temperaturerange, both of these coatings have dropped to a DI Water Contact Anglebelow 100 at about 210° C., and show a roughly equivalent DI WaterContact Angle below about 40 degrees between 350° C. and 500° C. Curves510 and 512, each show a three-layer AlOx/BTCSE Ox/PF6 coating. Curve510 represents the three-layer coating when the AlO_(x) layer is 21 Åthick, while Curve 512 represents the three-layer coating when theAlO_(x) layer is 95 Å thick. The BTCSE-generated oxide thickness was 115Å for the three-layer coatings illustrated in Curves 510 and 512. Thethree-layer coatings maintain a DI Water Contact Angle of 100 or greaterup to a temperature of about 440° C.

FIG. 8 shows a graph 800 illustrating the DI Water Contact Angle onscale 804, as a function of the substrate Temperature on scale 802.Graph 800 shows Curve 810 for a FDTS coating directly vapor deposited ona silicon wafer substrate; Curve 806 for a two-layer AlO_(x)/FDTS on thesilicon wafer substrate, where the AlO_(x) was generated fromtriethylaluminum precursor and was about 50 Å thick.; Curve 808 for athree-layer coating of AlO_(x)/TiO_(x)/FDTS on the silicon wafersubstrate, where the AlOx was generated from triethylaluminum precursorand was about 80 Å thick and the TiOx was generated from TiCl₄ precursorand was about 80 Å thick; Curve 812 for a three-layer coating ofAlO_(x)/SiCl₄-generated SiO_(x)/FDTS, where thetriethylaluminum-generated AlO_(x) layer was about 94 Å thick and theSiOx layer was about 148 Å thick; and, Curve 814 for a three-layercoating of AlO_(x)/BTCSE-generated SiO_(x)/FDTS, where thetriethylaluminum-generated AlOx layer was about 100 Å thick and theBTCSE SiOx layer was about 105 Å thick.

The results shown in Graph 800 are particularly unexpected because Curve810, where the FDTS was vapor deposited directly over the siliconsubstrate shows that this coating has better temperature stability thanboth curve 806 for a two layer coating of AlO_(x)/FDTS and curve 808 fora three-layer coating of AlO_(x)/TiO_(x)/FDTS. This comparison alsoconfirms an earlier conclusion that a three-layer coating where twolayers of metal-containing inorganic oxide underlie the SAM does notprovide the kind of performance observed for a three-layer coating ofthe kind representative of the present invention. This three-layercoating is at least a three layer coating, where the first layer is ametal-containing inorganic oxide adhesion layer, which may be an oxideof aluminum, zirconium, tin, or titanium (by way of example and not byway of limitation); the second layer is a silicon-comprising layer,which may be silicon oxide, silicon nitride, or silicon oxynitride (byway of example and not by way of limitation); and the third layer is aSAM which may be generated using one of the multitude of precursormaterials described previously herein. As previously discussed, thesecond layer may be replaced by a multiple of layers, where at least oneof the layers is the silicon-comprising layer.

Exemplary of the three-layer coating of the present invention are Curve812 which is a coating of AlO_(x)/SiCl₄-generated SiO_(x)/FDTS Curve812, and Curve 814, which is a coating of AlO_(x)/BTCSE-generatedSiO_(x)/FDTS. While the three-layer coating illustrated by Curve 812provides a significant improvement over the FDTS-generated SAM applieddirectly to the silicon substrate surface, the three-layer coatingillustrated by Curve 814 is far superior to all other coatings, showingtemperature stability at temperatures greater than 500° C. By way of apossible theory for this improved performance, it may be that theBTCSE-generated SiO_(x), after exposure to temperatures at which theorganic component would break down, provides a carbon-doped siliconoxide which improves the overall stability of the three-layer structure.This would indicate that other silicon-comprising intermediate layerswhich are carbon doped silicon oxides are likely to be stable to 500° C.

The unexpected result of a three-layer coating having a temperaturestability exceeding 500° C., achieved using an organicsilicon-comprising precursor to form an intermediate layer, opens thedoor to the use of higher processing temperatures for devices whileproviding a protective coating which resists moisture penetration to acoated substrate.

In addition to improved temperature stability and durability of the atleast three-layer multilayered coatings described above, we have beenable to achieve improved resistance to liquid immersion. SAM films arenot stable when deposited directly on many materials, especially noblemetals and polymers. The use of dual layer coatings where the SAM isapplied over an adhesion layer of silicon oxide allows for an improvedadhesion on some materials. However, the resistance of the coating toliquid has remained limited. For example, a dual layer ofBTCSE-generated SiOx used as an adhesion layer with a FDTS exteriorlayer, which is otherwise very stable on silicon and metal substrates,quickly loses the hydrophobic surface property and adhesion to polymersubstrates upon immersion in water as illustrated in FIG. 6 anddescribed in detail below. Therefore, such two-layer coatings can not beused on polycarbonate, polystyrene, poly methyl methacrylate, or othersimilar polymeric materials frequently used in micro fluidicapplications. The use of ALD metal oxides such as e.g. aluminum oxide asan underlying adhesion layer can improve adhesion of an overlyingfunctional organic coating to polymers and in addition provide a vaporbarrier. However, use of the metal oxide adhesion layers alone as abarrier to penetration by liquids does not work well.

We were surprised to find that by using a combination of a metal oxideand silicon-containing oxide beneath the organic functional layers, wewere able to obtain a triple-layer structure which exhibits excellentperformance at high temperatures, and which exhibits excellentperformance as a barrier layer not only with respect to vapors, but evenwith respect to immersion in liquids. This is despite the fact that theuse of either the metal oxide or the silicon-containing oxide alonebeneath the organic functional layer does not provide such thermal orliquid immersion performance. For example, plastic devices can be coatedwith a triple layer film (alumina+a BTCSE-generated siliconoxide+FDTS-generated SAM). This combination of three layers, eachserving the respective distinct function provides a unique andsurprising solution, a stable hydrophobic film shown in FIG. 6 withrespect to a polymethyl methacrylate (PMMA) substrate.

FIG. 6 shows a graph 600 illustrating the DI Water Contact Angle onscale 604, as a function of the Number of Days of DI Water Immersion onScale 602, for a two-layer AlOx/FDTS coating deposited on threedifferent substrates, compared with a three-layer AlOx/SiCl₄ Ox/FDTScoating on two substrates. The two-layer coating data is provided forpurposes of comparison of two-layer coatings of the kind previously usedwith coatings which are embodiments of the present invention.

With respect to FIG. 6, Curve 606 represents the performance of apolystyrene substrate coated with a 38 Å thick SiO_(x) adhesion layergenerated from a BTCSE precursor, with an exterior layer of an FDTSgenerated SAM. The hydrophobic surface (DI Water Contact Angle of 100degrees or more) had degraded after less than one day of immersion in DIwater. Curve 608 represents the performance of a polymethyl methacrylatesubstrate coated with a two-layer coating essentially equivalent to thatdescribed with reference to Curve 606. The hydrophobic surface degradedbelow the 100 degree contact angle in about one day. Curve 610represents the performance of a polystyrene substrate coated with atwo-layer coating essentially equivalent to those described withreference to Curves 606 and 608. The hydrophobic surface degraded belowthe 100 degree contact angle in about one and a quarter days.

The disappointing performance of the two-layer coatings described aboveis compared with the performance of two embodiment coatings of thepresent invention in FIG. 6. Curve 612 represents a nickel substratecoated with a three-layer coating of a 53 Å thick alumina adhesion layergenerated from a trimethyl aluminum precursor, followed by a secondprotective/mechanical structural layer of 115 Å thick SiOx generatedfrom a BTCSE precursor, with an exterior layer of FDTS-generated SAM.The degradation of the hydrophobic surface below the 100 degree contactangle appeared imminent, but had not occurred after 8 days of immersionin DI water. Curve 614 represents a polymethyl methacrylate substratecoated with a three-layer coating of a 53 Å thick alumina adhesion layergenerated from a trimethyl aluminum precursor, followed by a secondprotective/mechanical structural layer of 115 Å thick SiOx generatedfrom a BTCSE precursor, with an exterior layer of FDTS-generated SAM.The degradation of the hydrophobic surface below the 100 degree contactangle had not occurred after 8 days of immersion in DI water, andappeared to be extendable for a number of additional days.

FIG. 7 shows a Graph 700 illustrating the DI Water Contact Angle onscale 704, as a function of the number of days immersion in DI Water onscale 702. The three-layer coatings which are represented by variouscurves on Graph 700 were deposited on a NANO™ SU-8 polymer substrate.The SU-8 material was originally used as a negative photoresist, butmore recently, the material has been used as a polymeric substrate forsemiconductor devices, MEMS devices, and nanoimprint lithography molds.The SU-8 material is an epoxy-based photoresist material available fromMicro-Chem of Newton Mass. Curve 706 represents the change in DI watercontact angle for an AlO_(x)/TiO_(x)/FDTS coating after immersion in DIwater. Curve 708 represents the change in DI water contact angle for anTiO_(x)/SiCl₄-generated SiO_(x)/FDTS coating. Curve 710 represents thechange in DI water contact angle for an AlO_(x)/BTCSE-generatedSiOx/FDTS coating. The three-layer coating which makes use of analuminum oxide adhesion layer, followed by an organic-containing siliconprecursor to form the intermediate layer, followed by the SAM functionalexterior layer shows unexpected long term moisture resistance, havingsurpassed 20 days of immersion in DI water without loss of thehydrophobic surface characteristics of the functional exterior layer.This is the same kind of three-layer structure which exhibited the besthigh temperature performance.

The three-layer/multi-layered coatings described above are useful asrelease layers for Nanoimprint Lithography (NIL). NIL technology uses UVcurable resists or thermal resists during pattern replication bymechanical imprint. One of the challenges in NIL is fidelity of patternreplication and an ability to release the mold from the resists withoutmold contamination. While mold materials such as quartz and silicon withhigh density of hydroxyl groups can be easily coated with low surfaceenergy fluorocarbon SAM coatings metal molds such as e.g. stainlesssteel, nickel, or other metal alloys are difficult to coat due to pooradhesion of the coatings to the substrate and low resistance of thecoatings to mechanical and thermal stresses during the imprintingprocess.

We have experimented with using various protective film combinations onNIL nickel molds and stamps. The results are summarized in Table Twobelow.

TABLE TWO Summary of Imprint Results Using A Ni mold With VariousRelease Layer Coatings. Stiction to Pattern Release Film Resist FidelityContamination None X X X FDTS(SAM) X Δ X BTCSE SiO_(x)/FDTS(SAM) Δ Δ ΔAlO_(x)/FDTS(SAM) Δ O Δ AlO_(x)/BTCSE SiO_(x)/ O O O FDTS(SAM) X = bad,failure due to stiction; Δ = good for a limited number (<5) of imprints;O = good and reproducible during multiple (>10) imprint events.

Not surprisingly the AlO_(x)/BTCSE SiO_(x)/FDTS(SAM) three-layer coatingcombination resulted in the best release layer, as this triple-layercoating had been shown to deliver the best high temperature and liquidimmersion stability, indicative of good interlayer adhesion in-betweenthe layers and with the Ni substrate.

Ink-jet Protective Layers are another product application for thecoatings of the present invention. Polyimide (PI) is frequently used fordevice protection but its contact angle of about 70 deg. is to low toprevent ink spreading and smearing. A hydrophobic layer with goodadhesion to PI and compatible with water and other ink solvents is verydesirable. Polyimide material such as that used for ink-jet heads wascoated with the AlO_(x)/BTCSE SiO_(x)/FDTS(SAM) three-layer film stack.The sample was then soaked in water based ink at 70° C. for 2 hrs. Goodadhesion and hydrophobic contact angle were preserved as indicated byink de-wetting times of <5 sec. By comparison the dual-layer BTCSESiO_(x)/FDTS(SAM) film completely lost adhesion to the polyimidesubstrate under these conditions, and can not be used for thisapplication.

In biotechnology applications, the exterior functional layer of the atleast three layer coating of the present invention needs to becompatible with biological tissue, for example. It is also possible toprovide an improved three-layer hydrophilic film which comprises a metaloxide adhesion layer of the kind described above deposited in the mannerdescribed, followed by a silicon oxide-comprising layer where thesilicon oxide is formed from a carbon-containing precursor such as theBis(trichlorosilyl)ethane (BTCSE), followed by a hydrophilic functionallayer such as polyethylene glycol (PEG) applied over the siliconoxide-comprising layer. The BTCSE-generated silicon oxide-comprisinglayer, or a similar layer formed from an organic silicon-comprisingprecursor material tends to maintain its contact angle with a waterdroplet for an extended period of time, compared with a silicon-oxidelayer prepared using a non-carbon-containing precursor.

The above described exemplary embodiments are not intended to limit thescope of the present invention, as one skilled in the art can, in viewof the present disclosure expand such embodiments to correspond with thesubject matter of the invention claimed below.

We claim:
 1. A method of providing a durable protective coatingstructure which comprises at least three layers, said method comprising:vapor depositing a first layer deposited on a substrate, wherein saidfirst layer is a metal oxide adhesion layer selected from the groupconsisting of an oxide of a Group IIIA metal element, a Group IVB metalelement, a Group VB metal element, and combinations thereof; vapordepositing a second layer upon said first layer, wherein said secondlayer includes a silicon-containing layer selected from the groupconsisting of silicon oxide, silicon nitride, and silicon oxynitride;and vapor depositing a third layer upon said second layer, wherein saidthird layer is a functional organic-comprising layer, wherein saidfunctional organic-comprising layer is a SAM.
 2. A method in accordancewith claim 1, wherein said protective coating structure is stable attemperatures of 400° C. and higher.
 3. A method in accordance with claim1, wherein said second layer includes a layer of silicon-comprisingoxide generated from an inorganic precursor.
 4. A method in accordancewith claim 1, wherein said second layer includes a layer ofsilicon-comprising oxide generated from an organic precursor.
 5. Amethod in accordance with claim 1, wherein said coating is a three-layercoating, and said second layer is a silicon-comprising layer.
 6. Amethod in accordance with claim 5, wherein said first layer metal oxideis deposited using an ALD technique.
 7. A method in accordance withclaim 6, wherein said precursor materials used during said ALD processinclude an organometallic compound.
 8. A method in accordance with claim5, wherein said second layer is a silicon-comprising oxide which isdeposited using a CVD technique.
 9. A method in accordance with claim 8,wherein said CVD technique is an MVD technique.
 10. A method inaccordance with claim 5, wherein said third layer is a functionalorganic layer which is deposited using a CVD technique.
 11. A method inaccordance with claim 10, wherein said CVD technique employs astagnation reaction.
 12. A method in accordance with claim 1, whereinsaid first layer metal oxide is deposited using an ALD technique.
 13. Amethod in accordance with claim 12, wherein said second layer is asilicon-comprising oxide which is deposited using a CVD technique.
 14. Amethod in accordance with claim 13, wherein said CVD technique employs astagnation reaction.
 15. A method in accordance with claim 14, whereinsaid third layer is a functional organic layer which is deposited usingsaid CVD technique.
 16. A method in claim 12, wherein said third layeris a functional organic layer which is deposited using a CVD technique.17. A method in accordance with claim 16, wherein said CVD techniqueemploys a stagnation reaction.
 18. A method in accordance with claim 12,wherein said third layer is a functional organic layer which isdeposited using a CVD technique, said CVD technique employs a stagnationreaction.
 19. A method in accordance with claim 12, wherein saidprecursor materials used during said ALD process include anorganometallic compound.
 20. A method in accordance with claim 1,wherein said second layer includes a metal oxide and asilicon-comprising oxide.
 21. A method in accordance with claim 1, orclaim 3, or claim 4, wherein said at least three layers are deposited inthe same processing chamber without exposing the surface of said firstlayer or the surface of said second layer to ambient conditions.
 22. Amethod in accordance with claim 1, wherein said first layer is analuminum oxide layer; and wherein said second layer is a silicon oxidelayer.
 23. A method in accordance with claim 1, wherein said first layeris a titanium oxide layer; and wherein said second layer is a siliconoxide layer.
 24. A method of providing a durable protective coatingstructure which comprises at least three layers, said method comprising:vapor depositing a first layer deposited on a substrate, wherein saidfirst layer is a metal oxide adhesion layer selected from the groupconsisting of an oxide of a Group IIIA metal element, a Group IVB metalelement, a Group VB metal element, and combinations thereof; vapordepositing a second layer upon said first layer, wherein said secondlayer includes a silicon-containing oxide layer deposited from anorganosilane precursor having at least one silicon-carbon bond; andvapor depositing a third layer upon said second layer, wherein saidthird layer is a functional organic-comprising layer, wherein saidfunctional organic-comprising layer is a SAM.